The Cat Came Back is brilliant.

Have you considered Eric Bogel's Song of the Humpback - haunting and contains message that sympathises with plight of whale.

Song of the Humpback lyrics

For humour - there is Will the Turtle be Unbroken, sung to the tune of Will the Circle be Unbroken by Les Bqarker (I think).

Will the Turtle Be Unbroken lyrics

Good luck and wishing your event much success.